Molten salt catalysts

N.J. Bjerrum The group of Professor Bjerrum was the first to demonstrate NEMCA with a molten salt catalyst (Chapter 10) and also with a commercial V205-based S02 oxidation catalyst (Chapter 12). Both discoveries are of significant practical importance. 

Nakatsuji, Y., T. Kubo, M. Nomura, and S. Kikkawa, The Hydrocracking of Polynuclear Aromatic Hydrocarbons Over Molten Salt Catalysts., Bull. Chem. Soc. Jpn.,51, (2), 618-624,1978. 

P5C-3 In The kinetics of the oxidation of hydrogen chloride over molten salt catalysts, Chem. Eng. ScL, 23, 981 (1968), use Figure 2 in the article to determine the initial rate of HCI oxidation for the various oxygen concentrations. Include these data in Figure 3 together with the other data. Is it possible to explain the curvature in the line at small partial pressures of cldorine (the square root of the partial pressure of Cl ) ... 

Improved soot oxidation by fuel additives and molten salt catalysts... 

It was observed that the molten salt catalysts are highly active compared to the solid single oxide catalysts, probably as a result of the increased contact area due to wetting of the soot by the mobile catalyst. The oxidation rate is strongly increased by the presence of NO in the gas phase. 

The technology used for the application of a molten salt catalyst is a dominant issue. The soot particle has to be separated from the gas stream and brought into contact with the liquid catalytic phase, whereas the liquid phase should not be blown out or evaporated to the gas pheise. The surface structure that is in contact with the gas stream should be large to increase... 

While many studies have been carried out aimed at the feedstock recycling of rubber wastes by pyrolysis and hydrogenation processes (see Chapters 5 and 7), little information is found on the catalytic cracking and reforming of rubber alone. Larsen35 has disclosed that waste rubber, such as used tyres, can be degraded in the presence of molten salt catalysts with properties as Lewis acids, such as zinc chloride, tin chloride and antimony iodide. The decomposition proceeds at temperatures between 380 and 500 °C to yield gases, oil and a residue, in proportions similar to those obtained by simple thermal decomposition. 

S.6.2.2 Early Work on Supported Molten Salt and Ionic Liquid Catalyst Systems 5.6.2.2.1 High-temperature supported molten salt catalysts... 

The first supported molten salt catalyst systems date from 1914, where BASF filed a patent on a silica-supported V20s-alkali pyrosul te sulfur dioxide oxidation catalyst [48], which even today - as a slightly modified catalyst system - is still the preferred catalyst for sulfuric acid production [49]. However, it took many years to realize in the 1940s [50,51], that the catalyst system actually was a molten salt SLP-type system which is best described by a mixture of vanadium alkah sulfate/hydrogensulfate/pyrosulfate complexes at reaction conditions in the temperature range 400-600 °C with the vanadium complexes playing a key role in the catalytic reaction [49]. 

From the integrated peak areas, surface stoechiometries have been determined and compared with the chemical analysis data (see Table 1). The molten salt catalysts manifested superficial atomic M/Zr ratios close to the data of chemical analysis this apparently indicates a good dispersion of the doping element. 

This catalyst may also be referred to as the molten salt catalyst, as referred to by Idles et al, according to the catalyst materials of this type reported to date. It is well known that some of the transition metal oxides, alkaline, and alkaline-earth metal oxides promote carbon oxidation. These oxides are solid and immobile at room temperature but become mobile on the surfaces of soot and support materials on a micrometer scale above certain temperatures, the melting point, or so-called Tamman temperature. In such a mobile state, the catalyst can maintain contact with the soot while the soot surfaces are continually excavated by oxidation. 

Giakoumelou, L, Caraba, R., PSrvulescu, V., et al. (2002). First In Situ Raman Study of Vanadium Oxide Based SO2 Oxidation Supported Molten Salt Catalysts, Cattd. Letters, 78, pp. 209-214. 

Christodoulakis, A. and Boghosian, S. (2003). Molecular Structure of Supported Molten Salt Catalysts for SO2 Oxidation, J. Catal, 215, pp. 139-150. 

The preparation of catalyst formulations for soot oxidation follows different approaches. One approach is to increase the number of contact points between the soot particles and the catalysts by using fuel-borne catalyst additives or molten salt catalysts, which can wet the... 

Because most of the industrially significant reactions are exothermic, it is important that they may be conducted at as low temperatures as possible. Accordingly, in selecting a suitable molten salt catalyst it is necessary to choose low-melting solutions which, however, do not contain salts that... 

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